The present invention relates to a driver circuit, a physical quantity detection apparatus, an angular velocity detection apparatus, an integrated circuit device, and an electronic instrument.
A gyro sensor is provided in various electronic instruments such as a digital camera, a navigation system, and a mobile phone. An image stabilization process, a dead reckoning process, a motion sensing process, or the like is performed based on the magnitude of the angular velocity detected by the gyro sensor.
In recent years, a reduction in size and an increase in detection accuracy has been desired for a gyro sensor. For example, a vibrating gyro sensor that utilizes the resonance phenomenon of a crystal vibrator has been widely used as a gyro sensor that meets such a demand. In order to improve the detection accuracy of such a vibrating gyro sensor, it is effective to apply high energy to the vibrator so that oscillation (vibration) of the vibrator is stabilized. A driver circuit that amplifies a small oscillation current output from the vibrator to a maximum extent to generate a square-wave drive signal, and feeds back the drive signal to the vibrator has been known (see JP-A-2008-14932 and JP-A-2008-64663).
However, since the square-wave drive signal includes an odd-order harmonic component in addition to the resonance frequency component of the vibrator, a vibration mode other than the original vibration mode of the vibrator may also be excited, so that the detection accuracy may deteriorate.
The above problem may be solved by rounding the edge of the drive signal (i.e., reducing the harmonic component) by providing a capacitor having a sufficient capacitance at the drive terminal of the vibrator. However, since the time required for the vibrator to produce stable oscillations (vibrations) increases when increasing the capacitance of the capacitor, the startup time required for the voltage of the detection signal to reach an appropriate level after supplying power to the gyro sensor increases.